Chapter 10: Chemical Reactions and Equations – Important MCQs
1. A chemical reaction involves:
A. Only physical change
B. Change in shape
C. Rearrangement of atoms to form new substances
D. Change in color only
✔️ Answer: C. Rearrangement of atoms to form new substances
2. The correct way to represent a chemical reaction is:
A. Word problem
B. Word equation
C. Chemical equation
D. Mathematical expression
✔️ Answer: C. Chemical equation
3. Which of the following is the correct balanced chemical equation for the reaction of hydrogen and oxygen to form water?
A. H + O → H₂O
B. H₂ + O₂ → H₂O
C. H₂ + O₂ → 2H₂O
D. 2H₂ + O₂ → 2H₂O
✔️ Answer: D. 2H₂ + O₂ → 2H₂O
4. Which of the following observations helps to identify a chemical reaction?
A. Change in color
B. Evolution of gas
C. Change in temperature
D. All of the above
✔️ Answer: D. All of the above
5. The reaction: 2Mg + O₂ → 2MgO is an example of:
A. Decomposition reaction
B. Displacement reaction
C. Combination reaction
D. Double displacement reaction
✔️ Answer: C. Combination reaction
6. In which type of reaction does a single reactant break into two or more products?
A. Combination reaction
B. Displacement reaction
C. Decomposition reaction
D. Neutralization reaction
✔️ Answer: C. Decomposition reaction
7. The reaction: Zn + H₂SO₄ → ZnSO₄ + H₂ is an example of:
A. Combination reaction
B. Double displacement reaction
C. Decomposition reaction
D. Displacement reaction
✔️ Answer: D. Displacement reaction
8. A precipitate is:
A. A gas formed in a reaction
B. A solid formed from a solution
C. A colorless solution
D. A volatile substance
✔️ Answer: B. A solid formed from a solution
9. The brown coating on iron in moist air is called:
A. Rust
B. Corrosion
C. Tarnish
D. Oxidation
✔️ Answer: A. Rust
10. Which of the following is an example of a chemical change?
A. Melting of ice
B. Dissolving sugar in water
C. Burning of paper
D. Breaking of glass
✔️ Answer: C. Burning of paper
